1. Field of the Invention
The present invention relates to electrolytes containing aprotic organic solvents for use in high specific energy primary cells and, in particular, for lithium cells. Such electrolytes comprise one or several aprotic organic solvents which are compatible with lithium, and a solute in the form of an alkaline salt, such as lithium perchlorate, lithium hexafluoroarsenate, lithium hexafluorophosphate, lithium tetrafluoroborate, and so forth.
2. Description of the Prior Art
It has been noted previously that electrolytes having a solvent which is composed of a mixture of two organic substances, preferably a cyclic ether and an ester or a cyclic ether and a linear ether, may have higher conductivities than electrolytes having a solvent which is composed of a single organic substance at the same concentration of solvent. (See French Pats. Nos. 1,579,466, 2,054,736 and 2,176,568; respective U.S. equivalents: U.S. Pat. Nos. 3,511,716, 3,701,688 and 3,960,595.) This mixture has made it possible to use ethylene carbonate, which is solid at ordinary temperatures, as a solvent. It is also possible, however, that a mixture of two solvents will give only an additive effect, without increasing the conductivity (as the case of mixtures of tetrahydrofuran and dioxolane, for example), or even that the conductivity of the mixture is lower than that which would have been calculated knowing the proportions of the solvents and the conductivities of the pure solvents. For example, ether oxide has this effect with tetrahydrofuran, or acetic anhydride with dioxolane. The choice of solvents for composing the mixture is thus both important and difficult to predict in advance.